Primary Chronic Sclerosing Osteomyelitis: A New Diagnostic Tool

Abstract

Aims: Primary chronic sclerosing osteomyelitis is a rare and complex pathology and remains a diagnostic and therapeutic challenge. Our aim is to show our experience with a new diagnostic tool. Material and Methods: Four patients aged from 26 to 67 were referred to the department of oral and maxillofacial surgery of University Hospital CHUV in Lausanne between January 2010 and December 2018 for chronic mandibular pain without infectious signs nor symptoms. All patients underwent three-phase bone scintigraphy and anti-granulocyte antibody scintigraphy. Results: Three-phase bone scintigraphy demonstrated radiotracer uptake at the zone of pain, whereas anti-granulocyte antibody scintigraphy showed no uptake, thus rendering an infectious origin unlikely. Conclusion: A combination of the two different scintigraphies should be considered in order to guide the clinician in the diagnosis of primary chronic sclerosing osteomyelitis, thus preventing patients from undergoing unnecessary imagery and useless treatment, and also allowing an early diagnosis.

Primary chronic sclerosing osteomyelitis (PCSO) is a rare disease characterized by chronic osseous nonbacterial inflammation with no known etiology. It was initially described by Carl Garré in 1893 [1] as an osteomyelitis of the sclerosing type, with osseous deformation and enlargement but without suppuration, sequester or fistula. Patients describe principally chronic pain that is difficult to control, unilateral swelling, and sometimes trismus without symptoms or signs of infection for more than 4 weeks [2]. If the disease not only affects bone but also skin and joints, it is considered to be SAPHO syndrome (synovitis, acne, pustulosis, hyperostosis and osteitis) [3].

Radiologic characteristics are nonspecific. Early stages may show periosteal apposition associated with osteolytic lacunar images, and later stages can reveal a dense sclerotic bone with or without bone deformation. Histologically, there are no specific findings for primary chronic sclerosing osteomyelitis. Generally, medullary fibrosis, chronic inflammation and subperiosteal reaction can be found [4]. Blood markers are equally nonspecific. Bacterial cultures are often negative and are performed to exclude infectious osteomyelitis [5,6].

Treatment of PSO is divided into three steps, beginning with anti-inflammatory drugs. The second step is per os steroid administration, and the third step involves intra-venous bisphosphonates [7]. Intravenous bisphosphonate treatment protocol in our department consists in pamidronate administration of 15 mg for 3 days. If improvement in the symptoms, but not their disappearance, is noted, two more days of treatment are added. In case of recurrence of pain and other symptoms, the same procedure is repeated after 3 months [8]. Physiotherapy combined with medical treatment is highly recommended (Figure 1, Figure 2, Figure 3, Figure 4 and Figure 5).

Surgical treatment, such as decortication or even more invasive segmental mandibulectomy, has been described. However, it shows a high recurrence rate, even after additional procedures [9,10].

Diagnosis of this disease remains challenging. PCSO remains a diagnosis of exclusion using a combination of clinical and radiological arguments. An early and simple procedure for the diagnosis of PCSO is the combination of three-phase bone scintigraphy and anti-granulocyte antibody scintigraphy, as shown in these clinical cases. Three-phase bone scintigraphy is a diagnostic imaging tool that can be used for the diagnosis of osteomyelitis [11].

Bone scintigraphy uses diphosphonate molecules labelled with ^99mTc, which accumulate in the remodelling bone via incorporation into calcium hydroxyapatite. Bone radiotracer uptake depends on local blood flow and the extent of bone remodeling (mostly on the osteoblastic activity). Bone diseases such as osteomyelitis show increases in vascularization (hyperemia) and increases in radiotracer uptake due to the increase in bone turnover. A valuable advantage of this procedure is that these metabolic modifications are seen often weeks before classic radiological images show any lytic or sclerotic lesions.

Scintigraphy performed with anti-granulocytes antibodies labelled with Tc-99 m has an accuracy close to 90% for the detection of osteomyelitis [11].

The antibody binds specifically to granulocytes in vivo without altering their function. The marked granulocytes then migrate to the infected tissue due to chemiotactic attraction. Accumulation of these granulocytes in the infected tissue is dependent on the site of infection, the type and virulence of the pathologic agents, previous antibiotic or steroid treatment, and the quality of vascularization.

Overall, anti-granulocytes antibody scintigraphy has a good sensitivity (84%) and specificity (80%) for the detection of chronic infection in the peripheral skeleton.

In conclusion, the combination of the two different scintigraphies should be considered to help the clinician support the diagnosis of PCSO, thus preventing the patients from undergoing unnecessary imaging and useless treatments, while also allowing early diagnosis and adequate therapy.